This application is based upon and claims the benefit of priority from the prior Japanese Patent Application No. 2000-287691, filed Sep. 21, 2000, the entire contents of which are incorporated herein by reference.
1. Field of the Invention
The present invention relates to a cooling unit for forcing a heat generating component like a semiconductor package to be cooled with liquid-like cooling medium and an electronic apparatus provided with the cooling unit, such as a portable computer.
2. Description of the Related Art
An electronic apparatus like a portable computer has a micro processing unit (MPU) for processing multi-media information such as characters, voices and animation. This MPU tends to increase generation of heat during its operation accompanied by currently increased processing speed and multiple functions. Thus, in order to ensure a stable operation of the MPU, it is necessary to intensify heat radiation performance of this MPU.
Conventionally, a portable computer loaded with a MPU generating a large amount of heat is equipped with an air-cooling type cooling unit for forcing the MPU to be cooled. This cooling unit has a heat sink thermally connected to the MPU and an electric fan for supplying cooling air to this heat sink.
In this cooling unit, heat from the MPU is transmitted to the heat sink and then discharged out of the computer through a flow of cooling air. Therefore, because according to the conventional cooling method, cooling air serves as a cooling medium for depriving the MPU of heat, the cooling performance of the MPU mostly depends on air feeding performance of the electric fan. If the feeding amount of cooling air is increased to aim at intensifying cooling performance of the MPU, the rotation amount of the electric fan is increased, so that there is produced such a problem that a large noise may be produced. Additionally, because in the portable computer, a housing for incorporating the MPU and electric fan is designed so thin in a compact body, it is difficult to secure a space for accommodating a large electric fan having an excellent air feeding performance and an ideal air feeding path inside the housing.
In near future, it is expected that the processing speed of the MPU for the portable computer will be further accelerated and the MPU will become multi-functional, and accompanied by this trend, the heat generation of the MPU increases tremendously. Thus, the conventional forced air-cooling system has a fear that the cooling capacity for the MPU becomes short or reaches its limit.
As a means for improving this, for example, Jpn. Pat. Appln. KOKAI Publication No. 7-142886 has disclosed so-called liquid cooling system employing liquid having a higher specific heat than air as heat transferring medium.
According to this new cooling system, a heat receiving header connected to the MPU thermally is disposed inside the housing and a heat radiating header is disposed inside the display housing supported by this housing. The heat receiving header and the heat radiating header are connected to each other through a circulating pipe in which liquid-like cooling medium flows.
Because according to this cooling system, cooling medium circulates between the heat receiving header and the heat radiating header, heat from the MPU is transmitted to the heat receiving header and after that, transferred to the heat radiating header via the cooling medium. Heat transferred to the heat radiating header is discharged to the atmosphere by diffusion by heat conduction to the display housing. For the reason, the heat radiating header is connected thermally to the display housing and the display housing is composed of metallic material having excellent heat conductivity.
Therefore, such liquid cooling system is capable of transferring heat of the MPU more effectively than the conventional forced air cooling system, thereby raising the cooling performance of the MPU.
Meanwhile, heat of the MPU transferred from the heat radiating header to the display housing is discharged to the atmosphere from the surface of the display housing through natural convection and heat radiation. Thus, as the amount of heat transferred to the display housing increases, the surface temperature of the display housing is raised. As a result, if user happens to touch the surface of the display housing when opening/closing the display housing or carrying the computer, he or she may feel discomfort or heat.
Further, according to the liquid cooling system, a heat radiating header inside the display housing is connected to a heat receiving header inside the housing through a circulating pipe. Thus, if a necessity of removing this display housing from the housing occurs to carry out maintenance on the interior of the display housing, the heat receiving header thermally connected to the MPU needs to be removed from the housing temporarily.
However, disassembly of the periphery of such a precision MPU not only leads to damage of the MPU but also may make inappropriate the positional relationship between the heat receiving header and the MPU upon installation of the heat receiving header. Thus, this is unfavorable in terms of maintaining reliability of thermal connection between the MPU and the heat receiving header.
If the MPU is loaded on a place difficult to access like a rear face of a circuit board, a troublesome work of disassembling the housing and taking out the circuit board is required. This work can be said to be inappropriate in viewpoint of operation efficiency and therefore, there is a room for improvement at this point.
A first object of the present invention is to provide a cooling unit and an electronic apparatus capable of preventing a rise in temperature of the surface of a display unit.
A second object of the present invention is to provide an electronic apparatus, which allows a second housing to be removed from a first housing without releasing thermal connection between a heat receiving portion and a heat generating component and which can be disassembled/reassembled easily and maintain reliability of heat conduction favorably.
In order to achieve the above-described first object, according to a first aspect of the present invention, there is provided a cooling unit for use in an electronic apparatus having a computer main body containing a heat generating component and a display unit supported by the computer main body, the cooling unit comprising: a heat receiving portion thermally connected to the heat generating component and accommodated in the computer main body; a heat exchanging portion installed on the display unit; circulating means for circulating cooling medium between the heat receiving portion and the heat exchanging portion, the circulating means having a pipe line for introducing cooling medium heated by the heat receiving portion to the heat exchanging portion; and intermediate cooling means installed in the pipe line, the intermediate cooling means forcing the heated cooling medium flowing from the heat receiving portion to the heat exchanging portion to be cooled.
Further, in order to achieve the above-described first object, according to a second aspect of the present invention, there is provided an electronic apparatus comprising: a housing containing a heat generating component; a display unit supported by the housing; a heat receiving portion accommodated in the housing and thermally connected to the heat generating component; a heat exchanging portion installed on the display unit; circulating means for circulating cooling medium between the heat receiving portion and the heat exchanging portion, the circulating means being disposed throughout the housing and the display unit and having a pipe line for introducing cooling medium heated by the heat receiving portion to the heat exchanging portion; and intermediate cooling means installed in the pipe line of the circulating means, the intermediate cooling means forcing the heated cooling medium flowing from the heat receiving portion to the heat exchanging portion to be cooled.
With such a structure, heat from the heat generating component is transferred to the cooling medium by means of the heat receiving portion. This heat is transmitted to the heat exchanging portion through a flow of the cooling medium. The cooling medium cooled by heat exchange by means of the heat exchanging portion is returned to the heat receiving portion and receives heat from the heat generating component again. By repeating such a cycle, heat from the heat generating component is transmitted to the display unit effectively and discharged to the atmosphere.
The cooling medium heated through heat conduction from the heat receiving portion is cooled via the intermediate cooling means before it reaches the heat exchanging portion. Thus, the temperature of the cooling medium introduced by the heat exchanging portion can be lowered. Thus, the rise in temperature of the surface of the display unit can be suppressed despite discharging heat from the heat generating component from the display unit, so that a bad influence upon user using the electronic apparatus can be reduced to such a level having no problem.
In order to achieve the above-described second object, according to a third aspect of the present invention, there is provided an electronic apparatus comprising: a first housing containing a heat generating component; a second housing, the second housing being journaled detachably on a rear end of the first housing through a hinge device having a hinge shaft extending in the width direction of the first housing and having a rear face which is directed backward of the first housing when the second housing is rotated to a posture in which it stands up from the rear end of the first housing; a heat receiving portion accommodated inside the first housing and thermally connected to the heat generating component; a heat exchanging portion installed on the second housing, the heat exchanging portion being capable of being taken out of the rear face; and circulating means for circulating the cooling medium between the heat receiving portion and the heat exchanging portion, the circulating means comprising a first pipe line for introducing cooling medium heated by the heat receiving portion to the heat exchanging portion and a second pipe line for introducing cooling medium cooled by heat exchange by means of the heat exchanging portion to the heat receiving portion, the first and second pipe lines being disposed throughout the inside of the first housing and the inside of the second housing via backward of the hinge shaft, the rear face of the second housing having at least an opening portion at a position corresponding to the first and second pipe lines, the opening portion being covered with a removable lid.
With such a structure, heat from the heat generating component is transferred to the cooling medium by means of the heat receiving portion. This heat is transferred to the heat exchanging portion through the cooling medium flowing through the first pipe line. The cooling medium cooled by heat exchange by the heat exchanging portion is returned to the heat receiving portion through the second pipe line and receives heat from the heat generating component again. By repeating such a cycle, heat from the heat generating component is transmitted effectively to the second housing and discharged thereof to the atmosphere.
In order to remove the second housing from the first housing, first, the lid covering the opening portion of the second housing is removed so as to expose the first and second pipe lines introduced to the interior of the second housing through the opening portion. Subsequently, the heat exchanging portion is taken out in the direction of the rear face of the second housing and the first and second pipe lines continuous to this heat exchanging portion are taken out of the opening portion. Consequently, with the first and second pipe lines connected to the heat exchanging portion, this heat exchanging portion can be taken out of the second housing. Finally, the hinge device is removed from the first housing so as to separate the second housing from the first housing.
In order to install the second housing onto the first housing, the second housing is installed onto the first housing through the hinge device. After that, the heat exchanging portion is installed on the second housing in the direction of the rear face of the second housing. Next, the first and second pipe lines continuous to the heat exchanging portion are inserted into the second housing through the opening portion and then this opening portion is covered with the lid. As a result, the first housing and the second housing are connected to each other and the installation of the heat exchanging portion onto the second housing is completed.
Consequently, when removing the second housing from the first housing, it is not necessary to release thermal connection between the heat receiving portion and the heat generating component. Thus, a troublesome work of disassembling or reassembling portions corresponding to the heat generating component and heat receiving portion is not required, so that the removal of the second housing is facilitated. Further, no unreasonable force is applied to the heat generating component or the positional relationship between the heat generating component and the heat receiving portion is not changed, thereby making it possible to maintain reliability of thermal connection between the both.
In order to achieve the above-described second object, according to a fourth aspect of the present invention, there is provided an electronic apparatus comprising: a housing accommodating a heat generating component and being capable of being opened upward; a display unit supported by the housing; a heat receiving portion accommodated in the housing and thermally connected to the heat generating component; a heat exchanging portion installed on the display unit; and circulating means for circulating cooling medium between the heat receiving portion and the heat exchanging portion, the circulating means comprising a first pipe line for introducing cooling medium heated by the heat receiving portion to the heat exchanging portion and a second pipe line for introducing cooling medium cooled by heat exchange by means of the heat exchanging portion to the heat receiving portion, the first and second pipe lines being disposed throughout the inside of the housing and the inside of the display unit and being divided to upstream portions and downstream portions inside the housing, the upstream portions and the downstream portions being connected detachably through a joint, the joint having closing means for closing the first and second pipe lines when the first and second pipe lines are divided to the upstream portions and the downstream portions.
With such a structure, heat from the heat generating component is transferred to cooling medium by the heat receiving portion. This heat is transmitted to the heat exchanging portion through the cooling medium flowing through the first pipe line. Cooling medium cooled by heat exchange by means of the heat exchanging portion is returned to the heat receiving portion through the second pipe line and receives heat from the heat generating component again. By repeating such a cycle, heat from the heat generating component is transmitted to the second housing effectively and discharge thereof to the atmosphere.
In order to remove the second housing from the first housing, the first housing is opened upward so as to expose the first and second pipe lines introduced to the interior of the first housing. Next, the first and second pipe lines extending throughout the heat receiving portion and the heat exchanging portion are divided inside the first housing. Consequently, when removing the second housing having the heat exchanging portion from the first housing, the first and second pipe lines make no obstacle and the thermal connection between the heat receiving portion and the heat generating component does not have to be released. As a result, a troublesome work of disassembling/reassembling portions corresponding to the heat generating component and heat receiving portion is not required, so that the removal of the second housing is facilitated. Further, no unreasonable force is applied to the heat generating component or the positional relationship between the heat generating component and the heat receiving portion is not changed, so that reliability of thermal connection between the both can be maintained.
Further, if the upstream portions and the downstream portions of the first and second pipe lines are separated from each other, the first and second pipe lines are automatically closed. Therefore, no cooling medium leaks from the first and second pipe lines and thus, no special work for sealing the first and second pipe lines is required.
Additional objects and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objects and advantages of the invention may be realized and obtained by means of the instrumentalities and combinations particularly pointed out hereinafter.